<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    var message1 = "hello world"
    message1 = 'hello Coderwhy'
    message1 = 'aaa'

    // 1.let
    let message2 = '你好,世界'
    message2 = '你好,why'
    message2 = 123
    console.log(message2)

    // 2.const
    const message3 = '你好,世界'
    // message3 = '你好,why' // Uncaught TypeError: Assignment to constant variable.

    const info = {
      name: 'why',
      age: 18
    }
    console.log(info)
    info.name = 'kobe'
    console.log(info)
  </script>
</body>

</html>